Strange error at JScrollPane jScroll = new JScrollPane();

[Bruce Jin]

It always works but today I got this error at this statement:
JScrollPane jScroll = new JScrollPane();
Any ideas?
Thanks.
java.lang.ClassFormatError: Unknown constant tag in .class file
at sun.awt.image.OffScreenImage.createGraphics(Unknown Source)
at sun.awt.image.OffScreenImage.initBackground(Unknown Source)
at sun.awt.image.OffScreenImage.<init>(Unknown Source)
at sun.awt.windows.WComponentPeer.createImage(Unknown Source)
at java.awt.Component.createImage(Unknown Source)
at javax.swing.plaf.metal.BumpBuffer.<init>(Unknown Source)
at javax.swing.plaf.metal.MetalBumps.createBuffer(Unknown Source)
at javax.swing.plaf.metal.MetalBumps.setBumpColors(Unknown Source)
at javax.swing.plaf.metal.MetalBumps.<init>(Unknown Source)
at javax.swing.plaf.metal.MetalScrollBarUI.installDefaults(Unknown Source)
at javax.swing.plaf.basic.BasicScrollBarUI.installUI(Unknown Source)
at javax.swing.JComponent.setUI(Unknown Source)
at javax.swing.JScrollBar.updateUI(Unknown Source)
at javax.swing.JScrollBar.<init>(Unknown Source)
at javax.swing.JScrollBar.<init>(Unknown Source)
at javax.swing.JScrollPane$ScrollBar.<init>(Unknown Source)
at javax.swing.JScrollPane.createVerticalScrollBar(Unknown Source)
at javax.swing.JScrollPane.<init>(Unknown Source)
at javax.swing.JScrollPane.<init>(Unknown Source)
at XML2JTree1$1.<init>(XML2JTree1.java:51)
at XML2JTree1.<init>(XML2JTree1.java:51)
at XML2JTree1.main(XML2JTree1.java:319)

[Madhav]

hi bruce,
It must be a problem with your class itself.because this exception is Thrown when the Java Virtual Machine attempts to read a class file and determines that the file is malformed or otherwise cannot be interpreted as a class file.
hope this info helps you,
madhav